JPH0584832B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a device for detecting the fully closed position of an intake throttle valve of an internal combustion engine.

(Prior Art) In order to control the intake air amount of an internal combustion engine, an intake passage is provided with an intake throttle valve that opens and closes in conjunction with an accelerator pedal. The amount of fuel supplied to the internal combustion engine is controlled according to this amount of intake air, but for this purpose, in engines equipped with electronically controlled fuel injection devices, a signal from an air flow meter, etc. that measures the amount of intake air and the engine speed are used. Based on the signal, the amount of fuel to be injected is calculated so that the air-fuel mixture has a predetermined air-fuel ratio.

In this case, the target value of the air-fuel ratio, which is controlled according to the operating state of the engine, is changed so that the air-fuel ratio becomes richer than the normal stoichiometric air-fuel ratio during idling or acceleration, thereby improving engine drivability. Efforts are being made to improve the exhaust composition. Therefore, in addition to the intake air amount and rotational speed signals, signals representing the operating state and detection signals such as the opening degree of the intake throttle valve and the engine cooling water temperature are input to the control circuit that calculates the fuel supply amount. I have to.

For this reason, conventionally, to determine whether the engine is idling or accelerating at full throttle, a throttle switch that detects whether the throttle valve is fully closed or fully open has been placed near the throttle valve, as shown in Figures 9 and 10. (Jikko Sho 57)
-Refer to Publication No. 6961).

This throttle switch is mounted on a support bracket 1a against the outer wall of the throttle chamber in the intake passage.
A guide contact 3 that rotates in conjunction with the shaft 2 of a throttle valve (not shown) is provided on the housing 1 that is attached to the housing 1 via the guide contact 3.
A cam 5 is provided which rotates about a boss 4 supported by the housing 1 as the housing 1 rotates. A guide groove 6 is formed in the cam 5.
The center contact 7 guided by the cam 5 swings left and right due to the rotational angular displacement of the cam 5. On the left and right sides of the center contact 7 are idle contacts 8 that come into contact when the throttle valve is in the fully closed position.
A full contact 9 which also comes into contact when in the fully open position is provided oppositely.

Therefore, when the cam 5 rotates together with the shaft 2 of the throttle valve, the center contact 7 is guided by the guide groove 6 and swings from side to side, and at idle, when the throttle valve is fully closed, the center contact 7 and the idle contact 8 come into contact. When the throttle valve is fully opened during acceleration, the center contact 7 and the full contact 9 come into contact to output a fully open signal.

(Problem to be Solved by the Invention) In this throttle switch, since the contacts 7, 8, and 9 have a relative relationship with the shaft 2 of the throttle valve, the housing 1 is connected to the throttle chamber. To install it, it is necessary to accurately position it based on the relationship with the opening position of the throttle valve.Also, when adjusting the fully closed position of the throttle valve due to changes in engine idle speed over time, etc. At the same time, the fixing position of the housing 1 must be readjusted, and the installation work of such a throttle switch is troublesome.Moreover, this positioning accuracy requires detection of the fully closed and fully open positions of the throttle valve as a throttle switch. Because of the dependence on accuracy, this positioning requires highly accurate adjustment work.

Furthermore, with this throttle switch, when the fully closed position of the throttle valve is regulated by the first idle cam, such as when the engine is warmed up, it is virtually impossible to determine the fully closed state of the throttle valve. There was also the problem that the fully closed throttle valve could not be detected until some time after the engine started.

The present invention aims to solve such problems.

(Means for solving problems) The present invention is constructed as shown in FIG.

The fully closed position of the intake throttle valve 12 in the intake passage 11 is determined by the first idle cam 1 depending on the engine cooling water temperature.
3, and the fully closed position of the throttle valve 12 is gradually decreased as the water temperature rises after the engine is started. On the other hand, a throttle valve opening detection means 14 outputs a signal proportional to the opening of the throttle valve 12;
Similarly, a water temperature detection means 15 is provided which outputs a signal proportional to the cooling water temperature. Means 16 is provided for storing a predetermined upper limit value of the fully closed position of the throttle valve 12 in accordance with the cooling water temperature. Further, the minimum opening degree of the throttle valve 12 after the engine is started is stored as a fully closed determination reference value based on the output of the throttle valve opening detection means 14, and this value is sequentially updated when the minimum opening degree is updated. A storage means 17 for storing information is provided. Then, a means 18 is provided for determining whether or not the current actual opening degree of the throttle valve 12 is equal to or lower than a fully closed upper limit value at the cooling water temperature stored in advance at that time. The updated fully closed judgment reference value is compared with the current actual opening degree of the throttle valve 12 when it is below the upper limit value, and when this difference is smaller than a preset value, the throttle valve 12 is fully closed. means 19 for determining that.

(Function) Therefore, the minimum opening degree of the throttle valve, which is the reference value for determining whether the throttle valve 12 is fully closed, is determined by the first idle cam 13 during warm-up immediately after starting the engine. The throttle valve 12 is accurately set at each time, including when it is forcibly opened, and by comparing this fully closed judgment reference value with the actual throttle valve opening, it can be determined whether the throttle valve 12 is fully closed or not. be judged. Therefore, the fully closed position of the throttle valve 12 can be accurately determined immediately after the engine starts, and even if the fully closed position of the throttle valve 12 fluctuates over time or due to readjustment, special Fully closing of the throttle valve 12 can always be correctly detected without requiring correction or modification.

(Example) Examples of the present invention will be described below based on the drawings.

In FIG. 2, an intake throttle valve 12 installed in an intake passage 11 opens and closes in conjunction with an accelerator pedal (not shown), and its fully closed position (minimum opening degree)
is regulated by a first idle cam 13 that operates in response to engine cooling water temperature (in other words, engine temperature). The throttle valve fully closed position characteristic by the first idle cam 13 is set as shown in FIG. The degree of opening decreases, and at the end of warm-up, the restriction by the first idle cam 13 is released, and the throttle valve 12 returns to its original fully closed position where it is mechanically restrained due to the passage and the like. A throttle position sensor (potentiometer) 21 is attached in conjunction with the shaft 20 of the throttle valve 12. This throttle position sensor 21 outputs a voltage proportional to the opening degree of the throttle valve 12, and its detection opening range is set larger than the actual operating angle of the throttle valve 12. Even if the closed position becomes smaller than the fully closed angle at the initial stage of adjustment, the throttle position sensor 21 can detect this. On the other hand, a water temperature sensor 22 is provided that outputs a voltage according to the cooling water temperature as the engine temperature, and the output signals of these sensors 21 and 22 are converted from analog signals to digital signals by an AD converter 23, and A microcomputer 2 for determining the fully closed position of the throttle valve 12 along with an engine speed signal, a transmission gear position signal, etc.
4 is input. This microcomputer 24
At the same time, it calculates and outputs various control signals such as fuel injection amount and ignition timing necessary to control the engine, and its memory circuit 25 stores various preset data and calculation results. be done. This memory circuit 25 is connected to a backup power source 26 so that the memory can be retained even if the power to the internal combustion engine is cut off.

Next, a calculation operation performed by the microcomputer 24 for determining the fully closed position of the throttle valve 12 will be described with reference to FIGS. 3 to 5.

This calculation is repeated, for example, for a predetermined short period of time or in synchronization with engine rotation, but first, in step 31, the first idle cam 13 corresponding to the cooling water temperature Tw regulates the cooling water temperature based on the output of the water temperature sensor 22. Throttle valve fully closed upper limit value
Search TVOTW. This throttle valve fully closed upper limit value
TVOTW is set in advance as a characteristic that changes as shown in FIG. 7 with respect to water temperature Tw. Fig. 6 shows the change in the opening degree of the throttle valve 12 at the fully closed position regulated by the first idle cam 13, and Fig. 7 shows the upper limit of the variation in this characteristic, and the minimum value is 0. It differs from Figure 6 in certain respects.

Next, in step 32, the minimum value TVOMiN of the throttle valve opening until the water temperature reaches the water temperature Tw after engine startup is added to the above TVOTW and the fully closed value TVOiNT at the throttle valve fully closed position at the end of warm-up. The size is compared with. Here, TVOMiN is a reference value for comparing and determining the fully closed position of the throttle valve opening, and is the minimum value of the voltage output by the throttle position sensor 21 until the water temperature reaches the specified temperature after engine startup. The value is stored as described below, but when the calculation is performed for the first time after the engine is started, it is set to a predetermined value.
In addition, TVOiNT is the output value of the throttle position sensor 21 when the first idle cam 13 falls down after warming up and the throttle valve 12 returns to its original fully closed position. In the first calculation immediately after starting the engine, the values used the last time the engine was operated, which are held in the memory circuit 25 by the backup power supply, are used.

As mentioned above, TVOTW is the upper limit value for the increase in the throttle valve fully closed opening determined according to the operating angle when the first idle cam 13 is operating, and TVOiNT is the upper limit value for the increase in the throttle valve fully closed opening when the first idle cam 13 is operating. Since it means the initial value of the throttle valve opening after the idle cam 13 falls, TVOTW+
TVOiNT provides an upper limit for the throttle valve fully closed value, which is determined by the water temperature during warm-up. Step 32 compares this with the previous throttle valve minimum value. As a result, if TVOMiN is smaller than this upper limit value, it is left as is, but if it is larger, step 33 is performed.
Correct it to match the upper limit value. This corrective action is performed especially when TVOMiN is set to a predetermined value, such as when the first calculation is started immediately after the engine is started.
TVOMiN is an appropriate value corresponding to the water temperature at that time.

Next, as an operation to update the above minimum value, in step 34, TVOMiN and throttle position sensor 2, which is the throttle valve opening signal at that time, are
Compare the AD exchange output value TVO of No.1. here
If TVO is greater than TVOMiN, it means that there is a minimum value that has been updated so far, and a counter N is set to φ in step 35.
On the other hand, if TVO is smaller than TVOMiN, the counter N is compared with a predetermined value Nφ in step 36, and if N is smaller than Nφ, the process proceeds to step 38, but if it is larger, TVOMiN is set to TVO in step 37.
and clears the counter N (sets it to φ). In steps 34 to 37, if TVO is smaller than TVOMiN consecutively Nφ times, it means that TVOMiN is newly updated to TVO, which is the minimum value of the throttle valve opening at that time.

In step 38, TVOMiN and TVOiNT are compared, and if TVOMiN is smaller, it is assumed that cam drop has occurred due to the first idle cam, and in step 39, TVOiNT = TVOMiN.
Update TVOiNT. Step 40 is to determine whether the operating state at that time is an idle state after warming up. For example, if the water temperature is 75°C or higher, the gear position of the transmission is neutral, and the engine speed is
If it is below 900 rpm, it is determined that warming up is complete. If warm-up has been completed, in step 41
Set the current TVOMiN as TVOiNT. This is to restore the normal value when the value of TVOiNT becomes unduly small for some reason.

Up to this point, the process is to set a reference value that is a prerequisite for comparing and judging the throttle valve opening, and then moves to steps 42 to 44, where it is determined whether the actual throttle valve opening is fully closed. I do. In other words, the difference between the actual opening degree TVO of the throttle valve 12 and the previous minimum value TVOMiN is compared to see if it is greater than or equal to a predetermined value _T1 , and if it is less than that, it is determined that it is fully closed, and if it is In this case, it is determined in step 46 that the valve is not fully closed.

FIG. 8 shows how the water temperature Tw changes after the engine starts, and how the minimum throttle valve opening value (full-close judgment reference value) TVOMiN changes during actual driving.

In this case, TVOMiN is updated to the latest smaller value in sequence as the throttle valve fully closed opening becomes smaller due to the first idle cam as time passes after startup, but the actual throttle valve opening When the TVO is opened from fully closed, the update operation is stopped and will be updated when the TVO returns to the fully closed position.

Next, Figure 5 shows the upper limit for fully closing the throttle valve depending on the water temperature.
This is a flowchart for learning the water temperature characteristics of TVOTW, and the value of the upper limit TVOTW at the water temperature Tw at that time is
Learning is performed by weighted averaging with weight W from the TVOiNT values. TVOTW ₀ is the water temperature up to that point.
It means the upper limit value in Tw. Here, the above W is 0<
Select an appropriate value such that W≦1.

By doing this, variations in the characteristics of the first idle cam 13 that determines the idle opening degree of the throttle valve 12 due to changes in water temperature are absorbed, and the upper limit value characteristic corresponding to the actual characteristics of the first idle cam 13 is adjusted. It can be modified as follows.

(Effects of the Invention) As described above, according to the present invention, the minimum opening of the throttle valve, which is the reference value for determining whether the throttle valve is fully closed, is adjusted to the same value as during warm-up immediately after starting the engine. set accurately at all times, including when forced open by the first idle cam,
By comparing this fully closed judgment reference value with the actual throttle valve opening, it is determined whether the throttle valve is fully closed or not, so the fully closed position of the throttle valve opening can be accurately determined immediately after the engine starts. Even if the fully closed position of the throttle valve fluctuates due to changes over time or due to readjustment, there is no need for special corrections or corrections like in the past.
This has the effect of always correctly determining whether the throttle valve is fully closed.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 2 is a configuration diagram showing an embodiment of the invention, Figs. FIG. 7 is an explanatory diagram showing the characteristic of the fully closed valve opening degree, FIG. 7 is an explanatory diagram showing the characteristic of the throttle valve fully closed upper limit value, and FIG. 8 is an explanatory diagram showing the relationship between the minimum value of the throttle valve opening degree and the water temperature. FIG. 9 is a front view of a conventional throttle switch, and FIG. 10 is a sectional view of the same. 11... Intake passage, 12... Throttle valve, 13... First idle cam, 21... Throttle position sensor, 22... Water temperature sensor, 24... Microcomputer.

Claims (1)

[Claims] 1 The fully closed position of the intake throttle valve in the intake passage is controlled by a first idle cam according to the engine cooling water temperature, and the fully closed position of the throttle valve is gradually decreased as the water temperature rises after the engine starts. In the internal combustion engine, the throttle valve opening detecting means outputs a signal proportional to the opening of the throttle valve, the water temperature detecting means outputs a signal proportional to the cooling water temperature, and means for storing a predetermined upper limit value of a fully closed position of the throttle valve; and storing the minimum opening degree of the throttle valve after engine startup as a fully closed determination reference value based on the output of the throttle valve opening degree detection means; and storage means for sequentially updating this value when the minimum opening degree is updated, and whether the detected opening degree of the throttle valve is below the fully closed upper limit value at the cooling water temperature stored in advance. a means for determining whether or not the throttle valve is closed; and a means for determining whether or not the throttle valve is opened when the fully closed judgment reference value is equal to or lower than the upper limit based on the determination result, and when the difference is smaller than a predetermined value set in advance, the throttle valve is closed. A fully closed position detection device for a throttle valve for an internal combustion engine, comprising means for determining whether the valve is fully closed.